If life is found on Mars, what does it tell us about the odds of life being fairly common throughout the universe? And, following from that, what does it tell us about life as a phenomenon?

To wander off-piste (hence my putting this in FS), should we consider the possibility that the creation of life - abiogenesis - is a natural imperative?

To clarify: evolution could, if you were being generous, be considered as a sort-of vector arising from the natural 'forces' of inheritance, variation and selection. Is it possible that a similar set of influences could be driving the universe to create life in the same axiomatic way?

How can I think my way out of the problem when the problem is the way I think?

It does boil down to "things that are able to reproduce will, over time, be more and more common." So, at a chemical stand-point, chemicals that somehow produce other chemicals that are the same or similar will naturally spread. It is that first hurdle of reproducing that is tricky, though. So, I'd say, yes, if self-replicating chemicals can occur naturally, it would be fair (in my non-scientifically educated mind) to say there is a natural "vector" toward producing life. That says nothing about the rarity of it, though.

If life were discovered on Mars, it would still be hard to calculate probability of life, as we would go from a sample size of one to two. You'd end up with this sort of scenario. And even then, the sample size might still be one if it turns out Transpermia is a thing and Life hopped from Mars to Earth (or vice versa) via asteroid. If the life were unique enough, however, that we could be confident that it arose independent of Earth's life, then that would be very valuable data for Abiogenesis research. Once we nail down how Earth life and/or Mars life arose, or likely arose, we would be better able to determine probability of life elsewhere.

Whizbang wrote:Nah. They'd just say something like, "God created Earth life first... and then got bored and filled the rest of the cosmos with life as well. We're still super-special, though. Really."

Well, I was more thinking that it would be odd for God to use a completely different set of tools, since that contradicts the notion that he used the same tool-box on Earth to create different organisms. i.e. the creationist answer to "why does all life on earth appear to be related?" is "because god is the common creator, so all life shares a common technique".

How can I think my way out of the problem when the problem is the way I think?

If substantially-DNA-based life is found on Mars, then either it shares a common source with life on Earth (likely) or it did not (unlikely). The former case is interesting in a predictable sort of way, whereas the latter case would be extremely fascinating (as it implies that Earth-like life is uniquely probable in this universe).

If something like RNA-based life is found on Mars, then the same two possibilities exist, but the former explanation (common source) becomes slightly less likely and the latter explanation (independent origin) becomes slightly more likely. Either case is quite interesting and would give us a better idea of where to look for an abiogenesis vector.

Whizbang wrote:

tomandlu wrote:I'd hope for the first, but purely because it seems to offer the best odds for life being common in general. Also, it's one hell of a kick in the teeth for creationists.

Nah. They'd just say something like, "God created Earth life first... and then got bored and filled the rest of the cosmos with life as well. We're still super-special, though. Really."

Indeed. Like any conspiracy theory or pseudoscience, they will readily adapt their imaginations just enough to squeeze in contradictory evidence without ever admitting that it is contradictory. In fact, they'd probably claim something about how the Bible really "actually predicts this sort of thing". In particular, if it was DNA-based life, then they'd be screeching about "common design" in mere seconds.

tomandlu wrote:I was more thinking that it would be odd for God to use a completely different set of tools, since that contradicts the notion that he used the same tool-box on Earth to create different organisms. i.e. the creationist answer to "why does all life on earth appear to be related?" is "because god is the common creator, so all life shares a common technique".

A completely different form of life or an RNA-based life would be immediately embarrassing, but after the initial shock they'd bounce back with something like, "Every form of life that God created was designed to be uniquely suited to its environment, and so we could expect God to use unique biochemistry if he chose to populate alien worlds. This is obviously evidence of God's intelligence and purposefulness in design! It couldn't be anything else, because ARGUMENT FROM INCREDULITY LA LA LA LA"

Copper Bezel wrote:Going to echo the naw. Their core argument went down at Darwin. Everything since has been handwaving.

I do think a separate abiogenesis event would be an incalculably important data point, at hazard of mixed metaphors there. It's the absolute least guessable term in the Drake equation.

Well, to put the opposite, more pessimistic, spin on it, if life on Mars was related to life on Earth, then they've got a half-way decent argument on their side, and we're having to assume, without direct evidence, something that explains it.

How can I think my way out of the problem when the problem is the way I think?

Copper Bezel wrote:Going to echo the naw. Their core argument went down at Darwin. Everything since has been handwaving.

I do think a separate abiogenesis event would be an incalculably important data point, at hazard of mixed metaphors there. It's the absolute least guessable term in the Drake equation.

Well, to put the opposite, more pessimistic, spin on it, if life on Mars was related to life on Earth, then they've got a half-way decent argument on their side, and we're having to assume, without direct evidence, something that explains it.

There have been plenty of rocks blasted off of Mars that hit Earth, and plenty of rocks that were blasted off Earth and hit Mars. Moreover, lots of those events took place during the time period that Mars was wetter AND the sun was warmer. So a Martian origin for DNA-based life, subsequently finding its way to Earth, is by no means far-fetched and may in fact solve more problems than it suggests.

Alternately, if there are subtle differences between Martian DNA-based life and Earth DNA-based life that we are able to observe and quantify, this could conceivably lead us to a solution for how independent abiogenesis could (or even must have) come about, again placing us much further ahead than we are now.

But no matter what the discovery was, creationists would claim it as evidence. They always do. No matter what is discovered, they will say "Evolution and atheistic random chance cannot explain this or would have predicted something else, but this fits perfectly with our latest interpretation of the Bible!"